Pieris rapae
Cabbage White
Family:Pieridae
Family Description:
Alternate Common Name: Small White.
Note: This species is listed with the genus name Artogeia by some authors.
Description:
Caterpillar: The caterpillar is small, typically less than 1 inch long. It is green to bluish green, dotted lightly with tiny black dots, and striped lengthwise with yellow along the back and a row of yellow dashes along the side. The body is covered with short, white hairs.
Adult: The butterfly is medium-sized, with a wingspan of 1 ¾ to 2 ¼ inches. It varies in appearance slightly between the sexes and the seasons. Generally, the upperside is white to yellowish white. The forewing is marked with brownish to black shading at the tip; there is a single black spot in males, two in females. The hindwing is entirely white. Underneath, most of the forewing is white while its tip, and the hindwing, are light yellowish green to grayish green. Butterflies from the first and last generations of each year (early spring and late fall, respectively) tend to be smaller, with more white than yellow and very little black.

Range:
This widespread species ranges from central Canada south throughout the entire U.S. into Mexico. It occurs in almost all of Idaho.

Habitat:
It occurs in virtually all open areas, most often in gardens, cultivated fields, and in urban habitats.

Diet:

Caterpillar: Caterpillars feed on the leaves of a variety of plants, primarily members of the mustard family (Brassicaceae), the caper family (Capparidaceae), and the nasturtium family (Tropaeolaceae).
Adult: Butterflies drink flower nectar, preferring purple, blue and yellow flowers.

Ecology:
 The number of generations of caterpillars each growing season varies with the length of that season, ranging from two to three in the north and as many as eight in the south. Caterpillars can cause damage to gardens and certain crops. Pupae overwinter in a physiological state called diapause. Butterflies typically can be observed from the last frost of spring until the first frosts of autumn. Studies of their flight patterns indicate that they are able to fly significant distances, and tend to fly in a single direction on a given day, but that the preferred direction of flight changes from one day to the next. This species was introduced in Canada and in California in the 1860s, from Europe.

Reproduction:
 Males actively patrol in search of receptive females. Females lay yellowish white eggs singly on the leaves of host plants.

Conservation:
Idaho Status: Unprotected nongame species.
Global Rank:

G5; populations are widespread, abundant, and secure.

References:
Ferris, C. D. and F. M. Brown. (eds.) 1981. Butterflies of the Rocky Mountain States. Univ. of Oklahoma Press, Norman, Oklahoma, USA, 442 pp.

Opler, P. A., H. Pavulaan, and R. E. Stanford. 1995. Butterflies of North America. Jamestown, North Dakota, USA: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/distr/lepid/bflyusa/bflyusa.htm (Version 05Nov98).

Opler, P. A. and A. B.Wright. 1999. A Field Guide to the Western Butterflies. Second Edition. Peterson Field Guide Series. Houghton Mifflin Company, New York, New York, USA, 540 pp.

Pyle, R. M. 1981. National Audubon Society Field Guide to North American Butterflies. Alfred A. Knopf, Inc., New York, New York, USA, 924 pp.

Scott, J. A. 1986. The Butterflies of North America. Stanford University Press, Stanford, California, USA, 583 pp.

Stanford, R. E. and P. A. Opler. 1993. Atlas of Western U.S.A. Butterflies (Including Adjacent Parts of Canada and Mexico). Published by authors, Denver, Colorado, USA, 275 pp.